Frogs with lesions of the pretectum region are studied for visual responses elicited by food, threat, barriers and apertures. Deficits are compared with frogs in which the optic chiasm has been split. In both groups, an additional lesion of rostral thalamus is made in some animals to test localization of residual visual functions. Cuts between tectum and pretectum are made to evaluate the role of pretectal-to-tectum projections in the frog's ability to detour around barriers. Unilateral pretectal lesions are made in the effort to induce wrong way retinopretectal projections, and subsequent wrong-way barrier avoidance. The normality of optic projections are checked in many of these cases by use of anterograde transport of HRP from the retina.